feat(`forge test`): add an option to continue fuzzing run on assertion failure

[forkforkdog]

Component

Forge

Describe the feature you would like

Description:
Currently, Foundry’s invariant tests stop execution upon encountering the first assertion failure, ending the entire fuzzing campaign.

Feature Request:
Add an option to allow the fuzzing campaign to continue running until all configured runs are completed, even if assertion failures are encountered.

Rationale:
This feature would enable continuous fuzzing in an "Echidna-style" manner, where failing assertions are collected throughout the run without interrupting the campaign. Certain assertion failures require long-running fuzzing campaigns (e.g., 4+ hours), and stopping on the first failure can hinder the discovery of additional issues.

Expected Behavior:
When the continuous_run option is enabled, the fuzzer should:

1. Continue running despite encountering assertion failures.

2. Log all failures encountered during the campaign.

3. Upon manual cancellation (e.g., CTRL+C/CMD+C) or completion of the configured runs/timeout, present all call traces for reproducing the assertion failures.

Example Configuration:

[invariant]
continuous_run = true

Example Output:

test/fuzzing/FuzzPositions.sol:FuzzPositions                                     
    ↪ invariant_GLOB_01: [9/4294967295] Runs  
    ❌ Failures: 2

Additional context

No response

[0xalpharush]

Once this mode is added, it will be possible that there are duplicate reproducers. To deduplicate them, we can only store new reproducers which do not cover the same edges in the hitmap. This requires re-running the reproducers, keeping the metadata around, and comparing new reproducers to the old prior to persisting them